The UK's most complete GLP-1 guide
Every Question Answered. Every Side Effect Explained.
- How GLP-1 medications work
- Mounjaro vs Wegovy compared
- Injection instructions
- Side effects & solutions
- What to eat on treatment
- FAQs answered
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Weight Loss Sachets — What You Need to Know
Weight loss sachets are powdered supplement products marketed for weight management, but they're not the same as prescription weight loss medication. In the UK, most sachets sold over-the-counter are dietary supplements with limited clinical evidence. If you're looking for evidence-based weight management support, prescription options like GLP-1 injections (Wegovy and Mounjaro) are available through NHS specialist services or private prescribing. This guide explains what sachets are, how they differ from proven treatments, and your actual options for effective weight loss in the UK.
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Calculate Your BMI Instantly
Enter your height and weight below. Supports both imperial (stone & lbs) and metric (kg). Results include NHS category, healthy weight range, and ethnicity adjustments.
What Is BMI and Why Does It Matter?
Body Mass Index (BMI) is the most widely used screening tool for assessing whether your weight falls within a healthy range. Used by the NHS, GPs, and weight management services across the UK, BMI provides a quick snapshot of your weight relative to your height. The formula is simple: your weight in kilograms divided by your height in metres squared (kg/m²).
While BMI isn't a perfect measure — it doesn't account for muscle mass, bone density, or fat distribution — it remains the standard first step in identifying potential weight-related health risks including type 2 diabetes, cardiovascular disease, high blood pressure, and certain cancers.
The NHS also recommends adjusted thresholds for people of South Asian, Chinese, or Black African heritage — a BMI of 23 or above is classified as overweight, and 27.5 as obese. Our calculator includes this adjustment as a one-click toggle.
Over-the-Counter Weight Loss Sachets vs Prescription Medication
Over-the-counter weight loss sachets typically contain ingredients like glucomannan (soluble fibre), caffeine, green tea extract, or plant-based compounds claimed to support appetite control or metabolism. However, most lack robust clinical trial evidence for significant weight loss. They're regulated as food supplements under UK law, not medicines, which means they don't undergo the same rigorous testing as prescription drugs.
In contrast, prescription weight loss medication like Wegovy (semaglutide) and Mounjaro (tirzepatide) are licensed medicines with extensive clinical trial data. Wegovy is a GLP-1 receptor agonist approved for weight management in UK adults. Clinical trials showed participants lost an average of approximately 15% of body weight on Wegovy, alongside a reduced-calorie diet and increased physical activity. Mounjaro, a dual GIP and GLP-1 receptor agonist, showed average weight loss of 15–21% in clinical trials. Individual results vary, but these medications have proven safety and efficacy profiles.
For weight management in the UK, GLP-1 weight loss injections offer stronger clinical evidence than sachets. You can try our GLP-1 weight loss calculator to estimate potential outcomes at different doses.
Clinically BackedWeight Loss
No appointments. No waiting rooms. Just care — from a UK-regulated online pharmacy.
How It Works
Three simple steps to understand your weight and take action.
Enter your height and weight in our free calculator. Get your BMI, NHS category, healthy weight range, and ethnicity-adjusted thresholds instantly.
If your BMI suggests you're overweight or obese, explore our GLP-1 calculators to project potential weight loss on Mounjaro or Wegovy.
Use our progress tracker to log your weight weekly, visualise your journey with charts, and stay motivated — all stored privately in your browser.
Free Weight Loss Tools & Guides
Everything you need to understand your weight, explore medication options, and track your progress — completely free.
How to Access Prescription Weight Loss Treatment in the UK
If you're interested in evidence-based weight loss medication rather than sachets, you have two main routes. NHS access: Referral to a tier 3 specialist weight management service through your GP. Eligibility typically requires a BMI of 30 or above (or 27+ with weight-related health conditions like type 2 diabetes or hypertension). NHS availability varies by region and waiting lists can be lengthy.
Private access: Available through GPhC-registered online prescribers following an online clinical assessment. This route doesn't require NHS referral and is typically faster. Use our free BMI calculator to check whether you might be eligible, then discuss options with a prescriber or your GP. Remember, prescription weight loss medication works best alongside lifestyle changes—diet and physical activity remain essential for sustainable results.
- Dual GIP/GLP-1 receptor agonist
- Up to 22.5% body weight loss (SURMOUNT-1)
- Weekly injection, dose escalation over 20+ weeks
- Available via private prescription in the UK
- Doses: 2.5mg → 5mg → 7.5mg → 10mg → 12.5mg → 15mg
- GLP-1 receptor agonist
- Up to 15–17% body weight loss (STEP trials)
- Weekly injection, 5-step dose escalation
- NHS & private prescription available
- Doses: 0.25mg → 0.5mg → 1mg → 1.7mg → 2.4mg
Mounjaro vs Wegovy: Head-to-Head
A side-by-side comparison of the two most popular GLP-1 weight loss medications available in the UK.
| Feature | Mounjaro | Wegovy |
|---|---|---|
| Drug class | Dual GIP/GLP-1 agonist | GLP-1 agonist |
| Active ingredient | Tirzepatide | Semaglutide |
| Avg. weight loss | 15–22.5% | 12–17% |
| Key trial | SURMOUNT-1 (2022) | STEP 1 (2021) |
| Max dose | 15 mg weekly | 2.4 mg weekly |
| Escalation period | 20–32 weeks | 16–20 weeks |
| Administration | Weekly injection (pen) | Weekly injection (pen) |
| NHS availability | Private prescription only | NHS & private |
| Approx. private cost | £150–£250/month | £150–£300/month |
| Common side effects | Nausea, diarrhoea, constipation | Nausea, vomiting, diarrhoea |
Data sourced from SURMOUNT-1 and STEP 1 clinical trials. Costs are approximate and vary by provider. Always consult a prescriber.
Am I Eligible for Weight Loss Medication?
In the UK, eligibility for GLP-1 weight loss medications like Mounjaro and Wegovy is based on your BMI and overall health profile.
- BMI of 30 or above (obese)
- Age 18 or over
- No contraindicated conditions
- Committed to lifestyle changes
- BMI of 27 or above
- Plus type 2 diabetes
- Or high blood pressure
- Or obstructive sleep apnoea
Use our BMI calculator to check whether your BMI falls within the eligible range.
How We Built These Tools
Every calculator and guide on myweightcheck is built with accuracy and transparency in mind. Our BMI calculator uses the standard WHO formula with NHS-aligned category thresholds. Our GLP-1 projections are modelled on published clinical trial data from SURMOUNT and STEP studies.
All data stays on your device. We don't require sign-ups, and we don't store your health information on any server. Your progress tracker saves data locally in your browser using localStorage, so only you can see it.
We're based in the UK and our tools are designed specifically for UK users — supporting stone & lbs by default, referencing NHS guidelines, using NICE-approved medication data, and linking to GPhC-registered pharmacies.
Frequently Asked Questions
Common questions about BMI, weight loss medications, and our free UK tools.
Are weight loss sachets available on the NHS?
Most over-the-counter weight loss sachets are not available on the NHS because they're classified as food supplements, not medicines. The NHS does fund prescription weight loss medication through specialist tier 3 services for eligible adults. If you meet the eligibility criteria (BMI 30+, or 27+ with comorbidities), ask your GP about referral to a specialist weight management service.
Do weight loss sachets actually work?
Most commercial weight loss sachets lack strong clinical trial evidence for significant weight loss. Some fibre-based sachets may help you feel fuller temporarily, but they're not a substitute for calorie reduction and lifestyle changes. Prescription GLP-1 medications like Wegovy have robust clinical evidence showing meaningful weight loss when combined with diet and exercise.
What's the difference between sachets and GLP-1 injections?
Sachets are unregulated food supplements with limited evidence. GLP-1 injections (Wegovy, Mounjaro) are prescription medicines with extensive clinical trial data showing consistent weight loss results. GLP-1 medications work by suppressing appetite and regulating blood sugar, whereas sachets typically rely on fibre or stimulants with less proven effect.
Can I get weight loss sachets prescribed by my GP?
Your GP is unlikely to prescribe commercial weight loss sachets because they're not licensed medicines and lack strong evidence. However, if you're eligible, your GP can refer you to a specialist weight management service where prescription weight loss medication may be considered. Check your eligibility using our free BMI calculator.
What's the safest way to lose weight in the UK?
The NHS recommends sustainable weight loss of 0.5–1 kg per week through reduced-calorie diet and increased physical activity. For additional support, prescription weight loss medication (available on NHS or privately) can help alongside lifestyle changes. Always consult your GP or a healthcare professional before starting any weight loss treatment or supplement.
Ready to take control of your weight loss journey?
Start with a free BMI check, explore your GLP-1 options, or begin tracking your progress today. No sign-up. No cost. Just results.